s-Triazine (1,3,5-triazine) and pyrimidine derivatives have been researched in the fields of synthetic resins, synthetic fibers, dyes and agricultural chemicals and a great number of such compounds have been synthesized. In the field of pharmaceuticals, researches have been made with respect to antitumor, anti-inflammatory, analgesic and antispasmodic activities. Especially, hexamethylmelamine (HMM) is well-known which has been developed as analogue of anti-malignant-tumor agent triethylenemelamine (TEM) (see, for example, non-patent reference 1).
TEM is known as alkylating agent and is s-triazine derivative having cytotoxic antitumor activity. HMM has been marketed in Europe under the indications for the treatment of ovarian and small cell lung cancers, and its action on solid cancers have attractive.
Among the s-triazine derivatives, imidazolyl-s-triazine derivatives which exhibit cytotoxic and selective aromatase inhibitory activities have been proposed as medicine for estrogen-dependent diseases such as endometriosis, multicystic ovarium, mastopathy, endometrium carcinoma and breast cancer (see, for example, patent reference 1).
In order to expand antitumor activities of HMM and to decrease aromatase inhibitory activities of imidazolyl-s-triazine derivatives, we, the inventors, studied to find s-triazine and pyrimidine derivatives with substitution of benzimidazole ring for imidazole ring (see, for example, patent references 2 and 3).
We developed the studies for further enhancement of the antitumor activities in these compounds to find s-triazine and pyrimidine derivatives with specific substituents at position 2 of benzimidazole ring (see, for example, patent reference 4).
non-patent reference 1: B. L. Johnson et al. Cancer, 42: 2157-2161 (1978)
    patent reference 1: WO93/17009    patent reference 2: WO99/05138    patent reference 3: WO00/43385    patent reference 4: WO02/088112